Laser Absorptometer for Detection of Trace Species

9301915随着大气污染的增加和公众对由此造成的环境破坏的新的、日益增长的认识，需要新的技术来测量大气中痕量物种的浓度。在实验室中对密封的空气样本进行分析的提取方法价格昂贵，不适用于连续的、就地监测浓度。科学研究实验室(SRL)将开发一种名为激光干涉吸收计(LIA)的仪器来满足这一需求。该仪器的基础是对脉冲激光被干涉仪一臂中的痕量物质吸收后立即发生的光路变化的干涉测量。这一新方法将导致痕量气体监测技术的突破。它将允许首次以百万分之(Ppt)的水平对痕量气体浓度进行快速现场测量，比基于其他方法监测现场痕量物种的仪器灵敏度高100-1000倍。在第一阶段，确定了LIA的特性，并设计了适用于ppt痕量气体测量的LIA。在第二阶段，SRL将对包括氯氟烃(CFCs)在内的几种痕量气体进行实验研究和演示快速ppt检测，这些气体是导致臭氧层耗尽的主要污染物，被认为是全球变暖的重要贡献者。在一个私人资助的第三阶段后续项目中，SRL将开发一种能够测量工业CFCs和其他污染物排放的商业仪器。

9301915 Flusberg With the increase in atmospheric pollution and a new, growing public awareness of resulting environmental damage, there is a need for new technology to measure the concentration of trace species in the atmosphere. Extractive methods, in which a sealed sample of air is analyzed in a laboratory, are expensive and are inapplicable to continuous, in situ monitoring of concentrations. Science Research Laboratory (SRL) will develop an instrument called a laser interferometric absorptiometer (LIA) to fill this need. The basis of this instrument is the interferometric measurement of the optical-path change that occurs immediately after a pulsed laser beam is absorbed by trace species present in one arm of the interferometer. This novel approach will lead to a breakthrough in the technology of monitoring trace gases. It will allow rapid in situ measurements of trace-gas concentrations to be made for the first time at parts-per-trillion (ppt) levels, 100-1000 times more sensitively than instruments based on other approaches to monitor trace species in the field. In Phase I the characteristics of a LIA were determined, and an LIA suitable for ppt trace-gas measurements was designed. IN Phase II, SRL will experimentally research and demonstrate rapid ppt detection of several trace gases including chlorofluorocarbons (CFCs), major pollutants that are responsible for depletion of the ozone layer and are considered significant contributors to global warming. In a privately funded Phase III follow-on program, SRL will develop a commercial instrument capable of measuring industrial emissions of CFCs and other pollutants.